Ok, one more guess here:
You know that MMS requires setting up a whole bunch of parameters (MMSC, proxy, etc.. There are usually sent by the provider via a configuration SMS on regular phones.
Would it be possible for any of the people not seeing the camera icon to put the SIM card inside another phone and make sure you are able to send/receive MMS? You might use another phone to configure your MMS parameters and then put back your card into the iPhone. Just a thought.
I haven't installed 3.0. It's sitting right here in front of me and I'm not sure if I should install it or not, since this is my main an only phone.